1. Field
This application relates to suspended cable transport systems commonly known as zip lines. More specifically, this application relates to trolleys for zip line or other suspended cable systems which allow riders to maintain control of their speed of descent while traversing along a suspended cable.
2. Prior Art
Common zip lines are thrill-ride systems which are predominantly applied to applications for amusement. A common zip line system includes a suspended cable (constructed of aluminum, steel or similar metallic material) stretched between, and rigidly affixed to, separate supporting structures. One end of the suspended cable is affixed to a support structure which is located at an elevation higher than that of the opposite end. The result is a downward slope of the suspended cable. The higher end of the suspended cable is referred to as the beginning-end, and the lower end is referred to as the ending-end. A common zip line trolley consists of either one or two pulleys affixed to a common pulley housing. The pulleys of the trolley are placed on top of the suspended cable and a rider holds on to, or is tethered to, the trolley via a conventional safety harness. The downward slope of the suspended cable facilitates a gravitational force which propels the trolley and rider along the suspended cable.
A common zip line ride consists of a rider placing a common trolley on top of a suspended cable at the beginning-end. The rider either holds on to the trolley or is tethered to it via a safety harness. The ride begins when the rider disembarks from the beginning-end traversing along the suspended cable. The ride is complete upon the rider reaching the ending-end.
Zip lines are used by individuals at their own personal locations as well as by businesses in commercial applications. Many commercial zip line canopy tours employ the use of multiple suspended cables allowing for a variety of rides for patrons. Common trolleys are most often constructed of steel, or similar rigid material. Unfortunately, they do not afford a rider the ability to control his or her speed of descent while traversing along the suspended cable. Devices and systems similar to zip lines are witnessed within the oil industry relating to lowering endangered personnel from oil derrick towers.
Zip line riders can be classified as one of two types. Type one, commonly referred to as a novice or beginner, typically has minimal experience with zip lines and is apprehensive about riding one. Novices often prefer to traverse along the suspended cable at a relatively slow speed. Type two, commonly referred to as a daredevil, is an experienced zip line rider seeking the ultimate thrill, normally through traversing along the suspended cable at a rapid speed.
Various types of braking systems for common zip lines are known within the art. The most common methods of zip line braking systems presently available include gravity braking, impact braking and frictional braking. None of the braking systems presently available for common zip lines allow a rider control of his or her speed in a safe, economical and easy-to-use manner.
A gravity braking method relies on the natural sag in the suspended cable coupled with the rider's weight to bring he or she to a stop. The ride ends at a point where the rider's momentum ceases to propel the rider along the suspended cable. Most common zip lines designed with this braking method are only able to utilize roughly 70.0%-80.0% of the entire length of the suspended cable. Additionally, this method of bringing riders to a stop is imprecise and unpredictable in that riders of different weight will each develop a different momentum. As a result, each rider may stop at a different location along the suspended cable. This can complicate and add expense to the manner in which a zip line course designer designs the means for riders to disembark the suspended cable. An additional problem with this braking method is the rider has no control of his or her speed while traversing along the suspended cable. As a result, riders may accelerate to a velocity beyond their comfort level.
Impact braking methods commonly utilize an elastic cord (often a bungee cord or other similar material) along with a small block. The block is affixed close to the ending-end and in a manner such that it can slide freely along the suspended cable. One end of the bungee cord is fastened to the block and the other end is rigidly affixed to a point on the ground. When a rider traversing along the suspended cable makes contact with the block, the bungee cord expands and brings the rider to a stop. Riders can often be slowed to a stop at a rapid deceleration rate and then be snatched backwards along the suspended cable due to the springing function of the elastic cord. This is referred to as the “whip-lash effect” and is an undesirable and potentially unsafe function typical of such an impact braking method. Riders of different weight will each have a different momentum, thus causing the elastic cord to respond differently to each rider. Similar to gravity braking methods, impact braking methods are also unpredictable and often do not allow for full utilization of the length of the suspended cable. Furthermore, riders have no control of their velocity while traversing along the suspended cable.
In addition to elastic cords, rubber tires affixed to the ending-end of a suspended cable are often used as an impact braking method. Rubber tires witness similar results and potential safety hazards as those experienced with elastic cords.
Another method of impact braking includes a person standing on the ground near the ending-end of the suspended cable. This person, known as a brakeman, holds a rope or elastic cord which is attached to a block that can slide along the suspended cable. As the rider intercepts the block, the brakeman restricts the rope's motion, thus slowing the rider, often abruptly. This is another imprecise and unpredictable braking method which can be unsafe for both rider and brakeman. Furthermore, employment of a brakeman is an added expense to a commercial zip line system.
Frictional braking can be the most dangerous among the common zip line braking methods. One form of frictional braking requires the rider to wear a glove. While traversing along the suspended cable, the rider squeezes the suspended cable with the hand wearing the glove. This creates dynamic friction along the suspended cable, thus slowing the rider. This can be dangerous in that the rider can wear a hole through the glove and rub his or her skin along the suspended cable. Another form of frictional braking requires the rider to drag his or her feet along the ground while approaching the ending-end. Both of these methods are unpredictable and dangerous as bodily harm can easily be experienced.
Other braking methods known within the art add considerable expense and complexity to a common zip line. Many are rigidly fixed to a particular suspended cable, thus not easily transportable among other suspended cables. They often include a complicated series of additional pulleys and cables which all must work in unison to be operational. Should any one piece of such a braking system malfunction, the entire braking mechanism and rider's safety can be jeopardized. Additionally, some braking methods apply frictional forces directly to the suspended cable, similar to the frictional braking method of the rider using a glove as previously described. As dynamic friction is created, premature degradation and deformation of the suspended cable occurs. This can compromise the structural integrity of the suspended cable, thus making it prone to premature failure. This adds expense to a common zip line system by requiring earlier replacement of the suspended cable as well as creating a potentially unsafe situation for riders. Suspended cable zip line systems are dangerous in their nature wherein the rider's safety is dependent upon the structural integrity of both the trolley and the suspended cable.
With regards to common trolleys, most utilize a single point of connection between the trolley and the rider's safety harness. A typical safety harness is normally made of nylon or other safety fabric. A fabric harness, coupled with a single point of connection to the trolley, creates the likelihood that the rider's position will twist while traversing along the suspended cable. Often times the rider may be facing sideways or even backwards during the ride due to this twisting effect. This can pose a serious safety hazard since the rider's feet may no longer be facing forward. Common trolleys and safety harnesses allowing riders to twist can be especially dangerous for a zip line system which relies upon riders using their feet to facilitate braking. For these systems, it is imperative for riders to have both feet facing forward and be ready to land on both feet at the end of the ride.
U.S. Pat. Nos. 7,637,213 and 7,404,360 and US Patent Application Publication 20100162917 to Cylvick describe a trolley intended for use on a suspended cable or zip line. This trolley comprises a single pulley with a series of brake pad segments which apply dynamic frictional forces to the suspended cable. Although the braking mechanism on Cylvick's device calls for a material to be used which is not intended to prematurely degrade the suspended cable, undesirable dynamic frictional forces are indeed created. These frictional forces will accelerate wear and can result in a premature lifespan reduction of the suspended cable. One embodiment of Cylvick's device relies predominantly upon the weight of the rider for speed control. Once the rider's weight is determined, the trolley is adjusted accordingly prior to the rider embarking upon a ride. Another embodiment of Cylvick's device does allow for a rider to pull a tether while traversing along the suspended cable. This tether operates in conjunction with, and is dependent upon, the rider's weight. The rider pulls the tether which counteracts the effect of the rider's weight on the braking mechanism. Thus, a rider is able to achieve a minimal degree of speed control during the ride. Cylvick's braking mechanism on this trolley utilizes a series of brake pad segments to provide the frictional braking force which is applied to the suspended cable. Replacement of these brake pads can be difficult in that the entire brake assembly must be detached from the trolley and disassembled. Furthermore, this particular trolley can be cumbersome to remove from the suspended cable. It does not afford itself to quick and easy switching among different suspended cables. Lastly, since the brake pads will wear and form to particular cable diameters, this trolley cannot safely be interchanged among different suspended cables each having different diameters.
U.S. Pat. No. 6,622,634 to Cylvick describes a trolley intended for use on a suspended cable or zip line. This trolley comprises a single pulley with a brake pad which applies frictional forces to the suspended cable. This frictional force is undesirable in that it accelerates wear and can prematurely jeopardize the structural integrity of the suspended cable. Furthermore, the speed of descent for this device is predetermined and preset based upon the elevation difference between the support structures. Thus, riders of different weights will traverse along the suspended cable at approximately the same speed. However, riders have no control of their speed during the duration of the ride. The braking mechanism of this apparatus also employs a V-shaped trap which assists in applying additional dynamic friction directly to the suspended cable. This trolley can be complicated to remove from the suspended cable in that partial disassembly is required.
U.S. Pat. No. 6,666,773 to Richardson describes a zip line system which applies a frictional force to the suspended cable. The rider's speed of descent is predetermined based upon the rider's weight and does not afford speed control to the rider during the ride. The braking mechanism of this apparatus also employs a V-shaped trap which assists in applying additional dynamic friction directly to the suspended cable.
US Patent Application Publication 20090255436 to Buckman describes a zip line braking system utilizing a series of pulleys and ropes along with a counterweight to bring the rider to a stop. This braking method affords the rider no speed control while traversing along the suspended cable. The effectiveness of this braking mechanism will vary depending upon the weight of each rider. The desired braking adjustment is achieved by a guide applying a dynamic frictional force directly to a connecting member which is attached to the counterweight. The guide applies the frictional force to the connecting member by squeezing it through a pair of gloves which he or she is wearing. Common zip lines are not inexpensive to construct with the suspended cable often being the most expensive component. The apparatus described by Buckman requires utilization of two suspended cables of equal diameter and tensile strength, thus instantly doubling the expense for a common zip line. The necessary combination of steel pulleys and other connecting members also adds considerable expense. This braking system is rigidly fixed to a particular zip line and does not allow for quick and easy transport among different suspended cables. Lastly, an additional person, the guide, may be necessary to enhance the braking action which also adds to the complexity and expense of this braking method.
U.S. Pat. No. 7,381,137 to Steele et al. describes a zip line braking and motion arrest apparatus utilizing a braking block coupled with a series of pulleys along with braking and anti-rollback devices. This apparatus does not allow the rider any control of his or her speed. The pulleys, struts and crossbar described will add considerable expense to a common zip line. Also, this apparatus is rigidly fixed and not easily transportable among other suspended cables.
US Patent Application 20020162477 to Palumbo describes a braking system utilizing a series of cables, mechanical motor drive and a speed control mechanism. This speed control mechanism can be comprised of either an air shock, nitrogen shock, hydraulic disc brake or magnetic disc brake system. The infrastructure and expense required to construct and operate such an apparatus is far beyond the means of a common zip line enthusiast.
U.S. Pat. No. 4,934,277 to Smith et al. describes an apparatus designed for the safe recovery of individuals stranded upon suspended cables such as ski lifts. A brake shoe is applied directly to the suspended cable and the force applied is dependent upon the rescuer's weight and a predetermined adjustment of the described lever arm. This adjustment must be predetermined and applied prior to the rescuer descending along the suspended cable. The design of this apparatus affords itself to a slow-moving rescue device and not necessarily for a rapid moving recreational zip line trolley.
U.S. Pat. No. 5,094,171 to Fujita describes an apparatus for use in allowing an oil derrick operator to safely escape an oil drilling rig or derrick. The braking mechanism for this apparatus consists of a dynamic brake located on the front sheave and a shoe brake located within the rear sheave. The sheaves must be double grooved such that the suspended cable can be double or triple wound around the sheaves. The dynamic brake setting is predetermined and adjusted prior to descent along the suspended cable, thus limiting or possibly eliminating altogether the operator's control of his or her speed. Furthermore, since the suspended cable is double or triple wound around the sheaves, transporting this apparatus to another suspended cable cannot be quickly or easily accomplished.
U.S. Pat. No. 4,442,918 to Rhoads, Sr. describes an apparatus intended for allowing an endangered person to escape from an elevated structure. The braking system for this apparatus employs an automatic brake which controls the descent of a trolley along a suspended cable. The automatic brake is comprised of a fluid pump and a cable reel of non-uniform diameter. The intent of this apparatus is beyond the scope of a common zip line and would be cost prohibitive to apply to such a system.
U.S. Pat. No. 1,935,711 to Hecox et al. describes an oil derrick escape device. This apparatus allows the escapee speed control by applying a frictional force directly to the suspended cable. This device is not intended, or practical for use on a common zip line system.
U.S. Pat. No. 301,923 to Reisdorff describes a fire escape device used in conjunction with a suspended rope strung from the top of a burning building. The device utilizes a single pulley and the braking mechanism comprises two separate components. The first is a series of outwardly projecting spurs or barbs which embed into the rope to retard the speed of descent. The second is a lever which allows the escapee to apply a frictional force to the side of the pulley, thus further slowing the speed of descent. This device would not operate as intended if used in conjunction with a metallic suspended cable rather than a rope. The outwardly projecting spurs will not embed into a metallic suspended cable as they will with a rope. Thus, this speed-retarding feature cannot be realized on a common zip line system.